#!/usr/bin/env python3
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

"""
This script downloads and repacks official rust language builds
with the necessary tool and target support for the Firefox
build environment.
"""

import argparse
import errno
import hashlib
import os
import shutil
import subprocess
import tarfile
import textwrap
from contextlib import contextmanager

import requests
import toml
import zstandard


def log(msg):
    print("repack: %s" % msg, flush=True)


def fetch_file(url):
    """Download a file from the given url if it's not already present.

    Returns the SHA-2 256-bit hash of the received file."""
    filename = os.path.basename(url)
    sha = hashlib.sha256()
    size = 4096
    if os.path.exists(filename):
        with open(filename, "rb") as fd:
            while True:
                block = fd.read(size)
                if not block:
                    return sha.hexdigest()
                sha.update(block)
        log("Could not calculate checksum!")
        return None
    r = requests.get(url, stream=True)
    r.raise_for_status()
    with open(filename, "wb") as fd:
        for chunk in r.iter_content(size):
            fd.write(chunk)
            sha.update(chunk)
        return sha.hexdigest()


def check_call_with_input(cmd, input_data):
    """Invoke a command, passing the input String over stdin.

    This is like subprocess.check_call, but allows piping
    input to interactive commands."""
    p = subprocess.Popen(cmd, stdin=subprocess.PIPE)
    p.communicate(input_data)
    if p.wait():
        raise subprocess.CalledProcessError(p.returncode, cmd)


def setup_gpg():
    """Add the signing key to the current gpg config.

    Import a hard-coded copy of the release signing public key
    and mark it trusted in the gpg database so subsequent
    signature checks can succeed or fail cleanly."""
    keyid = "0x85AB96E6FA1BE5FE"
    log("Importing signing key %s..." % keyid)
    key = b"""
-----BEGIN PGP PUBLIC KEY BLOCK-----

mQINBFJEwMkBEADlPACa2K7reD4x5zd8afKx75QYKmxqZwywRbgeICeD4bKiQoJZ
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Mve696B5tlHyc1KxjHR6w9GRsh4=
=5FXw
-----END PGP PUBLIC KEY BLOCK-----
"""
    check_call_with_input(["gpg", "--import"], key)
    check_call_with_input(
        ["gpg", "--command-fd", "0", "--edit-key", keyid], b"trust\n5\ny\n"
    )


def verify_sha(filename, sha):
    """Verify that the checksum file matches the given sha digest."""
    sha_filename = filename + ".sha256"
    with open(sha_filename) as f:
        # Older sha256 files would contain `sha filename`, but more recent
        # ones only contain `sha`.
        checksum = f.readline().split()[0]
        if checksum != sha:
            raise ValueError("Checksum mismatch in %s" % filename)
        return True
    log("No checksum file for %s!" % filename)
    return False


def fetch(url, validate=True):
    """Download and verify a package url."""
    base = os.path.basename(url)
    log("Fetching %s..." % base)
    if validate:
        fetch_file(url + ".asc")
        fetch_file(url + ".sha256")
    sha = fetch_file(url)
    if validate:
        log("Verifying %s..." % base)
        verify_sha(base, sha)
        subprocess.check_call(
            ["gpg", "--keyid-format", "0xlong", "--verify", base + ".asc", base]
        )
    return sha


def install(filename, target):
    """Run a package's installer script against the given target directory."""
    log("Unpacking %s..." % filename)
    subprocess.check_call(["tar", "xf", filename])
    basename = filename.split(".tar")[0]
    log("Installing %s..." % basename)
    install_cmd = [os.path.join(basename, "install.sh")]
    install_cmd += ["--prefix=" + os.path.abspath(target)]
    install_cmd += ["--disable-ldconfig"]
    subprocess.check_call(install_cmd)
    log("Cleaning %s..." % basename)
    shutil.rmtree(basename)


def package(manifest, pkg, target):
    """Pull out the package dict for a particular package and target
    from the given manifest."""
    version = manifest["pkg"][pkg]["version"]
    if target in manifest["pkg"][pkg]["target"]:
        info = manifest["pkg"][pkg]["target"][target]
    else:
        # rust-src is the same for all targets, and has a literal '*' in the
        # section key/name instead of a target
        info = manifest["pkg"][pkg]["target"]["*"]
    if "xz_url" in info:
        info["url"] = info.pop("xz_url")
        info["hash"] = info.pop("xz_hash")
    return (version, info)


def fetch_package(manifest, pkg, host):
    version, info = package(manifest, pkg, host)
    if not info["available"]:
        log("%s marked unavailable for %s" % (pkg, host))
        raise KeyError

    log("%s %s\n  %s\n  %s" % (pkg, version, info["url"], info["hash"]))
    sha = fetch(info["url"], info["hash"] is not None)
    if info["hash"] and sha != info["hash"]:
        log(
            "Checksum mismatch: package resource is different from manifest"
            "\n  %s" % sha
        )
        raise AssertionError
    return info


def fetch_std(manifest, targets):
    stds = []
    for target in targets:
        stds.append(fetch_package(manifest, "rust-std", target))
        # not available for i686
        if target != "i686-unknown-linux-musl":
            stds.append(fetch_package(manifest, "rust-analysis", target))
    return stds


def fetch_optional(manifest, pkg, host):
    try:
        return fetch_package(manifest, pkg, host)
    except KeyError:
        # The package is not available, oh well!
        return None


@contextmanager
def chdir(path):
    d = os.getcwd()
    log('cd "%s"' % path)
    os.chdir(path)
    try:
        yield
    finally:
        log('cd "%s"' % d)
        os.chdir(d)


def build_tar_package(name, base, directory):
    name = os.path.realpath(name)
    log("tarring {} from {}/{}".format(name, base, directory))
    assert name.endswith(".tar.zst")

    cctx = zstandard.ZstdCompressor()
    with open(name, "wb") as f, cctx.stream_writer(f) as z:
        with tarfile.open(mode="w|", fileobj=z) as tf:
            with chdir(base):
                tf.add(directory)


def fetch_manifest(channel="stable", host=None, targets=()):
    if channel.startswith("bors-"):
        assert host
        rev = channel[len("bors-") :]
        base_url = "https://s3-us-west-1.amazonaws.com/rust-lang-ci2/rustc-builds"
        manifest = {
            "date": "some date",
            "pkg": {},
        }

        def target(url):
            return {
                "url": url,
                "hash": None,
                "available": requests.head(url).status_code == 200,
            }

        for pkg in (
            "cargo",
            "rustc",
            "rustfmt-preview",
            "clippy-preview",
            "rust-analyzer-preview",
        ):
            manifest["pkg"][pkg] = {
                "version": "bors",
                "target": {
                    host: target(
                        "{}/{}/{}-nightly-{}.tar.xz".format(base_url, rev, pkg, host)
                    ),
                },
            }
        manifest["pkg"]["rust-src"] = {
            "version": "bors",
            "target": {
                "*": target("{}/{}/rust-src-nightly.tar.xz".format(base_url, rev)),
            },
        }
        for pkg in ("rust-std", "rust-analysis"):
            manifest["pkg"][pkg] = {
                "version": "bors",
                "target": {
                    t: target(
                        "{}/{}/{}-nightly-{}.tar.xz".format(base_url, rev, pkg, t)
                    )
                    for t in sorted(set(targets) | set([host]))
                },
            }
        return manifest
    if "-" in channel:
        channel, date = channel.split("-", 1)
        prefix = "/" + date
    else:
        prefix = ""
    url = "https://static.rust-lang.org/dist%s/channel-rust-%s.toml" % (prefix, channel)
    req = requests.get(url)
    req.raise_for_status()
    manifest = toml.loads(req.text)
    if manifest["manifest-version"] != "2":
        raise NotImplementedError(
            "Unrecognized manifest version %s." % manifest["manifest-version"]
        )
    return manifest


def patch_src(patch, module):
    log("Patching Rust src... {} with {}".format(module, patch))
    patch = os.path.realpath(patch)
    subprocess.check_call(["patch", "-d", module, "-p1", "-i", patch, "--fuzz=0", "-s"])


def build_src(install_dir, host, targets, patches):
    install_dir = os.path.abspath(install_dir)
    fetches = os.environ["MOZ_FETCHES_DIR"]
    rust_dir = os.path.join(fetches, "rust")
    patch_dir = os.path.join(os.environ["GECKO_PATH"], "build", "build-rust")

    # Clear and remake any previous install directory.
    try:
        shutil.rmtree(install_dir)
    except OSError as e:
        if e.errno != errno.ENOENT:
            raise
    os.makedirs(install_dir)

    # Patch the src (see the --patch flag's description for details)
    for p in patches:
        module, colon, file = p.partition(":")
        if not colon:
            module, file = "", p
        patch_file = os.path.join(patch_dir, file)
        patch_module = os.path.join(rust_dir, module)
        patch_src(patch_file, patch_module)

    log("Building Rust...")

    example_config = ""
    for example_toml in ("config.example.toml", "config.toml.example"):
        path = os.path.join(rust_dir, example_toml)
        if os.path.exists(path):
            with open(path) as file:
                example_config = file.read()
                break

    if "ignore-git" in example_config:
        omit_git_hash = "ignore-git"
    else:
        omit_git_hash = "omit-git-hash"

    # Rust builds are configured primarily through a config.toml file.
    #
    # `sysconfdir` is overloaded to be relative instead of absolute.
    # This is the default of `install.sh`, but for whatever reason
    # `x.py install` has its own default of `/etc` which we don't want.
    #
    # `missing-tools` is set so `rustfmt` is allowed to fail. This means
    # we can "succeed" at building Rust while failing to build, say, Cargo.
    # Ideally the build system would have better granularity:
    # https://github.com/rust-lang/rust/issues/79249
    base_config = textwrap.dedent(
        """
        [build]
        docs = false
        sanitizers = true
        extended = true
        tools = ["analysis", "cargo", "rustfmt", "clippy", "src", "rust-analyzer"]

        [rust]
        {omit_git_hash} = false
        use-lld = true

        [install]
        prefix = "{prefix}"
        sysconfdir = "etc"

        [dist]
        missing-tools = true

        [llvm]
        download-ci-llvm = false
        """.format(
            prefix=install_dir,
            omit_git_hash=omit_git_hash,
        )
    )

    # Rust requires these to be specified per-target
    target_config = textwrap.dedent(
        """
        [target.{target}]
        cc = "clang"
        cxx = "clang++"
        linker = "clang"

        """
    )

    final_config = base_config
    for target in sorted(set(targets) | set([host])):
        final_config = final_config + target_config.format(target=target)

    with open(os.path.join(rust_dir, "config.toml"), "w") as file:
        file.write(final_config)

    # Setup the env so compilers and toolchains are visible
    clang = os.path.join(fetches, "clang")
    clang_bin = os.path.join(clang, "bin")
    clang_lib = os.path.join(clang, "lib")

    env = os.environ.copy()
    env.update(
        {
            "PATH": os.pathsep.join((clang_bin, os.environ["PATH"])),
            "LD_LIBRARY_PATH": clang_lib,
        }
    )

    # x.py install does everything we need for us.
    # If you're running into issues, consider using `-vv` to debug it.
    command = ["python3", "x.py", "install", "-v", "--host", host]
    for target in targets:
        command.extend(["--target", target])

    subprocess.check_call(command, stderr=subprocess.STDOUT, env=env, cwd=rust_dir)


def repack(
    host,
    targets,
    channel="stable",
    cargo_channel=None,
    patches=[],
):
    install_dir = "rustc"
    if channel == "dev":
        build_src(install_dir, host, targets, patches)
    else:
        if patches:
            raise ValueError(
                'Patch specified, but channel "%s" is not "dev"!'
                "\nPatches are only for building from source." % channel
            )
        log("Repacking rust for %s supporting %s..." % (host, targets))
        manifest = fetch_manifest(channel, host, targets)
        log("Using manifest for rust %s as of %s." % (channel, manifest["date"]))
        if cargo_channel == channel:
            cargo_manifest = manifest
        else:
            cargo_manifest = fetch_manifest(cargo_channel, host, targets)
            log(
                "Using manifest for cargo %s as of %s."
                % (cargo_channel, cargo_manifest["date"])
            )

        log("Fetching packages...")
        rustc = fetch_package(manifest, "rustc", host)
        cargo = fetch_package(cargo_manifest, "cargo", host)
        stds = fetch_std(manifest, targets)
        rustsrc = fetch_package(manifest, "rust-src", host)
        rustfmt = fetch_optional(manifest, "rustfmt-preview", host)
        clippy = fetch_optional(manifest, "clippy-preview", host)
        rust_analyzer = fetch_optional(manifest, "rust-analyzer-preview", host)

        log("Installing packages...")

        # Clear any previous install directory.
        try:
            shutil.rmtree(install_dir)
        except OSError as e:
            if e.errno != errno.ENOENT:
                raise
        install(os.path.basename(rustc["url"]), install_dir)
        install(os.path.basename(cargo["url"]), install_dir)
        install(os.path.basename(rustsrc["url"]), install_dir)
        if rustfmt:
            install(os.path.basename(rustfmt["url"]), install_dir)
        if clippy:
            install(os.path.basename(clippy["url"]), install_dir)
        if rust_analyzer:
            install(os.path.basename(rust_analyzer["url"]), install_dir)
        for std in stds:
            install(os.path.basename(std["url"]), install_dir)
            pass

    log("Creating archive...")
    tar_file = install_dir + ".tar.zst"
    build_tar_package(tar_file, ".", install_dir)
    shutil.rmtree(install_dir)
    log("%s is ready." % tar_file)

    upload_dir = os.environ.get("UPLOAD_DIR")
    if upload_dir:
        # Create the upload directory if it doesn't exist.
        try:
            log("Creating upload directory in %s..." % os.path.abspath(upload_dir))
            os.makedirs(upload_dir)
        except OSError as e:
            if e.errno != errno.EEXIST:
                raise
        # Move the tarball to the output directory for upload.
        log("Moving %s to the upload directory..." % tar_file)
        shutil.move(tar_file, upload_dir)


def expand_platform(name):
    """Expand a shortcut name to a full Rust platform string."""
    platforms = {
        "android": "armv7-linux-androideabi",
        "android_x86": "i686-linux-android",
        "android_x86-64": "x86_64-linux-android",
        "android_aarch64": "aarch64-linux-android",
        "linux64": "x86_64-unknown-linux-gnu",
        "linux32": "i686-unknown-linux-gnu",
        "mac": "x86_64-apple-darwin",
        "macos": "x86_64-apple-darwin",
        "mac64": "x86_64-apple-darwin",
        "mac32": "i686-apple-darwin",
        "win64": "x86_64-pc-windows-msvc",
        "win32": "i686-pc-windows-msvc",
        "mingw32": "i686-pc-windows-gnu",
    }
    return platforms.get(name, name)


def validate_channel(channel):
    """Require a specific release version.

    Packaging from meta-channels, like `stable`, `beta`, or `nightly`
    doesn't give repeatable output. Reject such channels."""
    channel_prefixes = ("stable", "beta", "nightly")
    if any([channel.startswith(c) for c in channel_prefixes]):
        if "-" not in channel:
            raise ValueError(
                'Generic channel "%s" specified!'
                "\nPlease give a specific release version"
                ' like "1.24.0" or "beta-2018-02-20".' % channel
            )


def args():
    """Read command line arguments and return options."""
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--channel",
        help="Release channel to use:"
        " 1.xx.y, beta-yyyy-mm-dd,"
        " nightly-yyyy-mm-dd,"
        " bors-$rev (grab a build from rust's CI),"
        " or dev (build from source).",
        required=True,
    )
    parser.add_argument(
        "--patch",
        dest="patches",
        action="append",
        default=[],
        help="apply the given patch file to a dev build."
        " Patch files should be placed in /build/build-rust."
        " Patches can be prefixed with `module-path:` to specify they"
        " apply to that git submodule in the Rust source."
        " e.g. `src/llvm-project:mypatch.diff` patches rust's llvm."
        " Can be given more than once.",
    )
    parser.add_argument(
        "--cargo-channel",
        help="Release channel version to use for cargo."
        " Defaults to the same as --channel.",
    )
    parser.add_argument(
        "--host",
        help="Host platform for the toolchain executable:"
        " e.g. linux64 or aarch64-linux-android."
        " Defaults to linux64.",
    )
    parser.add_argument(
        "--target",
        dest="targets",
        action="append",
        default=[],
        help="Additional target platform to support:"
        " e.g. linux32 or i686-pc-windows-gnu."
        " can be given more than once.",
    )
    args = parser.parse_args()
    if not args.cargo_channel:
        args.cargo_channel = args.channel
    validate_channel(args.channel)
    validate_channel(args.cargo_channel)
    if not args.host:
        args.host = "linux64"
    args.host = expand_platform(args.host)
    args.targets = [expand_platform(t) for t in args.targets]

    return args


if __name__ == "__main__":
    args = vars(args())
    setup_gpg()
    repack(**args)